Technological Field
The present disclosure is related to devices and methods for monitoring physical activity of living beings and more specifically for calculating the cardiorespiratory fitness level and energy expenditure of a living being.
Description of the Related Technology
Current technologies for estimating energy expenditure (EE) and cardiorespiratory fitness (CRF) can provide useful insights about a living being's physical activity and health.
CRF can be estimated using maximal tests, but such tests require medical supervision and cannot be performed by everyone. There are also known methods, such as the one described in “Cross-Validation of the Polar Fitness Test via the Polar F11 Heart Rate Monitor in Predicting VO2Ma,” by Michael R. Esco, Emmanuel M. Mugu, Henry N. Williford, Aindrea N. McHugh and Barbara E. Bloomquist, in Journal of Exercise Physiology, 2011, which calculate CRF using sub-maximal tests. However, such techniques require both a specific test and repeating such specific test every time the CRF needs to be assessed.
In a similar way, current EE estimation techniques present also some limitations, for example, either provide inaccurate EE values, such as in “Branched equation modeling of simultaneous accelerometry and heart rate monitoring improves estimate of directly measured physical activity energy expenditure,” by S. Brage, in Journal of Applied Physiology, 96(1):343-351, Aug. 2003; or perform individual calibration using an indirect calorimeter, such as in “Hierarchy of individual calibration levels for heart rate and accelerometry to measure physical activity,” by S. Brage, U. Ekelund, N. Brage, M. A. Hennings, K. Froberg, P. W. Franks, and N. J. Wareham, in Journal of Applied Physiology, 2007, which requires a specific test with a very costly device.
Therefore, there is a need for ambulatory and/or more accurate and cheap automatic solutions for calculating cardiorespiratory fitness levels and energy expenditures of living beings, such as humans or animals, which may use wearable sensors and can be comfortably carried during activities of daily living.